The present invention relates, in general, to semiconductor devices, and more particularly, to a novel method of forming electrical connections between elements of a semiconductor device.
In the past, the semiconductor industry has utilized a variety of methods to interconnect the various elements used in forming a semiconductor device. Radio frequency (R. F.) power devices is one family of semiconductor devices that generally are formed by such methods. Typically, R. F. power devices are formed by connecting a large number of small individual transistors together in parallel. The amount of current to be carried by the R. F. power device determines the number of small transistors that are used.
One problem with large R. F. power devices is the area required to form the conductor or interconnect pattern. Generally, the reticle of a wafer stepping exposure system is used as a mask to expose photoresist on a semiconductor wafer. Often the pattern to be exposed is too large to fit onto one reticle of a wafer stepping exposure system. Consequently, the interconnect pattern is split into two overlapping sections that fit onto two separate stepper reticles. Using two reticles to form a conductor interconnect mask typically requires several critical alignments to ensure registration of the two images resulting from the two reticles. Such multiple exposures require precise alignment between the two images formed by the two stepper reticles. Also, the multiple exposures require twice as much time to expose the entire interconnect pattern thereby increasing manufacturing costs. Additionally, two sets of stepper reticles must be maintained thereby further increasing manufacturing costs.
Accordingly, it is desirable to have a method of forming large semiconductor devices that does not require more than one stepper reticle, that does not require precise alignment, and that reduces manufacturing costs.